Numerical simulation of compressible viscous mhd flows for reducing supersonic drag of blunt bodies

The possibility of reducing supersonic drag of blunt bodies by application of strong magnetic field (generated by magnets on the body surface) to the flow is considered in this paper. Some of the results reported in the Russian literature indicate that the shock structure in a slightly ionized gas (plasma) is significantly weaker than that in nonionized gases at the same temperature. For example, the shock standoff distance of a sphere moving at supersonic speed in a slightly ionized air heated to plasma temperature is considerably larger than in a nonionized air heated to die same temperature. Furthermore, the shock front is highly diffused, sometimes to the point of being scarcely visible besides lacking sharp boundary normally observed in photographs obtained under such conditions in nonionized gases. These concepts and others for shock wave modification/dissipation in supersonic flow are currently being investigated by the U.S. Air Force under the AJAX program. One of the concepts of interest is the effect of large magnetic field (approximately 2 Tesla or more) on supersonic flowfield about blunt bodies to evaluate the possibility of shock wave dissipation/elimination. This paper evaluates this concept by numerical simulation. The authors have recently developed a 2-D unsteady compressible viscous magnetohydro-dynamic code designated WSUMHD2D which has been validated for 2-D internal and external flows. This code is employed to investigate the concept of supersonic drag and heat transfer reduction by modification/dissipation of shock waves in the presence of strong magnetic fields. A series of numerical experiments for blunt body flows have been conducted by varying the Mach number, Reynolds number, and the intensity of the magnetic field to understand the physics of the phenomena and its potential for supersonic drag reduction in practical applications. These studies indicate the feasibility of supersonic drag reduction by the application of strong magnetic field.